Vibrator.



H. E. SHREEVE.

VIBRATOR.

APPLICATION FILED SEPT- 17. 1915.

1 ,284,4;80. Patented Nov. 12, 1918,

Fig.

v y I A unrrnn srrA'r s PATENT omen j HERBERT EDWARD SHREEVE, OF MILBURN, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPO- nn'rron on NEW YORK.

VIBRA'IOR.

Specification of Letters Patent.

Application filed September 17, 1915. Serial No. 51,281.

To all whom it may concern:

Be it known that I, HERBnnrE. SHREEVE, a subject of the King of Great Brltain, re-

siding at Milburn, in the county'of Essex and State of New Jersey, have invented certain new and useful Improvements in Vibrators, of which the following is a full, clear, concise, and exact description.

This invention relates to the generation of alternating current, and particularly to vibrators designed to deliver'pulsating direct current of high frequency to the primary of a transformer to produce alternating currents of high frequency in the secondary thereof for the purpose of testing circuits. Specifically the object of this invention is to provide a high frequencyvibrator of simple construction and at the same time adapted to A fine adjustments.

In accordance with this invention there are provided a motor and a transmitter element. The motor element comprises a vibratory reed held in operative relation with an electromagnet through the agency of a clamping device. An adjusting means carried by said clamping device is provided which functions to vary the effective lengthof said reed. The transmitting element includes a variable resistance element, a microphonic element being illustrated suitably supported so as to be capable of being brought into light contact engagement with said vibratory reed by virtue of an adjusting means. The specific structure and arrangement of these parts will be hereinafter more fully explained.

Figure 1 is a plan view of a vibrator embodylng the features of this invention; Fig.

2 is a side elevation taken on lines 22 of Fig. 1; and Fig. 3 illustrates diagrammatically the wiring arrangement of the vibrator contemplated by this invention.

Mounted upon one end of a base plate 1 is a supporting block 2 secured by means of screws 3. The inner surface of the block 2 is recessed so as to accommodate the base of the core of an electromagnet 4. Mounted upon the opposite end of the plate 1 by means of screws 5 is a U-shaped supporting block 6 having extending portions 7 and 8.

The recess between the portions-7 and 8 is large enough to permit the free movement of a clamping iece 9. The clamping piece 9 is held in a ed position by means of a set screw 10, one end of which engages said clamping piece by projecting inwardly intothe block 6. The end of the reed adjacent the outer end face of the extending portion 8 is bent at right angles and carries an adjusting screw 21 having its threaded end engaging suitable threads formed in the outer surface of said portion 8. The opposite end of the reed 11 is positioned in operative relation with the pole pieces of the magnet 4 for vibration thereby. Other suitable means can be substituted for the electromagnet 4 "to efl ect vibration of thereed 11, if desired.

A resilient member 12, having one of its ends rigidly secured in any suitable manner to the outer face of the extending piece 8 of the block 22, carries at its free end a variable resistance element, a microphonic element 13 being shown. The resilient member 12 is sirable, it is not absolutely-necessary that p the member 12 carrying the'element-l3 be resilient as any other suitable meanscan be used to secure adjustment between the element l3 and the reed 11. The microphonic element shown is of a standard form comprising an inclosing chamber 17 containing a pair of electrodes 18 separated by comminuted carbon. The front electrode has a contact point projecting through the wall of the chamber 17 which is adapted to engage a contact piece 19 carried by the reed 11. The contact piece 19 can be omitted if desired inwhich case the contact point on the front electrode would engage directly with the reed 11. The rear electrode is secured to the rear wall of chamber 17 and the complete element is fastened to the resilient member 12 by means of a nut 23 engaging-a threaded extension projecting from the rear wall of the chamber 17. ()bviously, however, any

sistance changes under different conditions of mechanical pressure may be used in place of the microphonic element 13 illustrated.

From the above description it will be seen that the reed 11 is movable in a longitudinal direction and its frequency of vibration, when acted upon by an external force,

may be varied by loosening the clamping piece 9 and turning the adjusting screw 21. I

By means of the adjusting screw 15 a fine contact relation may be obtained between the electrodes of the microphonic element and the reed 11. a 1

Fig. 3 illustrates diagrammatically th circuit relation of the elements described above. As shown, the motor and transmitter elements are preferably connected in se-,

ries with a battery, which is preferably'connected through a resistance to the primary of an induction coil. When the reed 11. is set in vibration either mechanically or by closure of the primary circuit it is evident that there will occur a cyclic variation of the resistance of the microphonic element and a consequent variation in' the primary current which variations will have a perio-.

dicity equal to the natural rate of vibration of the reed. These current variations in the rimary 'circuit which includes the winding of the electromagnet 4 will'cause a like a cyclic variation inthe pull on the'Teed and will therefore maintain the reed in a steady state of vibration.

The arrangement is thus seen to be capable'of producing in thesecondary winding of the transformer an alternating current of a definite sustained frequency depending on the natural period of the reed. Such currents have been found to have a wave close to a pure slnusoidal wave to be use 111 in making measurements form vsufiicientl of inductance, etc., at telephonic frequencies adjustment such that the circuit will be broken at the contact as in the ordinary in-- terrupter thus producing a different wave form.

What is claimed is:

1. A vibrator comprising a vibratory reed, means to effect vibration thereof, a variable resistance element to contact with said reed, means to vary the effective length of the reed to vary the frequency of vibration thereof, and means to adjust said element relative to said reed; the vibrations of said reed serving to vary 'the resistance of said element.

2. A vibrator comprising a base, a sup porting block mounted on said base, an elec- 3. A .vibrator comprising a base, a supporting block mounted on said base, an elec-- tromagnet, a vibratory reed carried b said block and positioned in operative re ation with said electromagnet, means for varying the efiective length of said reed, a variable resistance element, means to position said element for contact with said reed, and means to adjust said resistance element relative to said reed.

4:. A vibrator comprising a base, a supporting block carried thereby, a vibratory reed carried by said block, means to vibrate said reed positioned in operative relation to said "reed, means for varying theefi'ective length of said reed, a resilient member carriedby'said block, a variable resistance element carried by said member and adapted to engage said reed, and means cotiperating with said member to adjust said resistance element relative to said reed. In witness whereof, I hereunto subscribe 'my name this 27th day of August, A. D.

* HERBERT EDWARD sHREEVE; 

